Method, Apparatus, System and Program Product Supporting Efficient Eviction of an Entry From a Central Coherence Directory

摘要

In response to a memory access request missing in a central coherence directory of a data processing system, the central coherence directory issues a back-invalidate request and provides an indication of one or more processors possibly caching a copy of a victim memory block associated with a victim memory address. In response to the back-invalidate request, a memory controller initiates a lookup of coherency information for the victim memory address in the central coherence directory and, prior to receipt of the coherency information, speculatively issues a set of back-invalidate commands on one or more of multiple processor buses to invalidate any cached copy of the victim memory block. In response to receipt of the coherency information, the memory controller determines whether the set of speculatively issued back-invalidate commands was under-inclusive, and if not, removes a victim entry associated with the victim memory address from the central coherence directory.